|NEWS AND INFORMATION
|Year : 2014 | Volume
| Issue : 3 | Page : 184-185
News and Information
Ex BARC, Mumbai, Maharashtra, India
|Date of Web Publication||10-Apr-2015|
Ex BARC, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pushparaja. News and Information. Radiat Prot Environ 2014;37:184-5
[TAG:2]Protection of the Environment under Different Exposure Situations, ICRP Publication 124, Ann, ICRP 43 (1), 2014,
R. J. Pentreath et al.[/TAG:2]
The ICRP, in this document, describes the framework for the protection of the environment-related to the protection of animals and plants in their natural environment. The document describes different potential pathways of exposure and how the objectives of protection are met by the use of reference animals and plants (RAPs); their derived consideration reference levels, which relate radiation effects to doses over and above their normal local background natural radiation levels. Recommendations are also made by the commission to meet the stated objectives by use of representative organisms specific to a site.
The final chapter discusses the overall implications of the commission's work in this area to date. Appendices A and B provide some numerical information relating to the RAPs. Annex C considers various existing types of environmental protection legislation currently in place in relation to large industrial sites and practices, and the various ways in which wildlife are protected from various threats arising from such sites (source: www.iaea.org).
| Radiological Protection against Radon exposure, ICRP Publication 126, Ann, ICRP 43 (3), 2014, J-F, Lecomte et al.|| |
In this report, the ICRP provides updated guidance on radiological protection against radon exposure. The report has been developed considering the latest ICRP recommendations for the system of radiological protection, all available scientific knowledge about the risks of radon, and the experience gained by many organizations and countries in the control of radon exposure. The report describes the characteristics of radon exposure, covering sources and transfer mechanisms, the health risks associated with radon, and the challenges of managing radon exposure.
The commission recommends an integrated approach, based on the optimization principle, for controlling radon exposure, relying as far as possible on the management of buildings or locations in which radon exposure occurs. The report also provides recommendations on managing radon exposure when workers' exposures are considered as occupational, and the appropriate requirements of the commission should be applied (source: www.iaea.org).
| Why Polonium is Highly Radiotoxic?|| |
Polonium, (named after Poland), with symbol Po and atomic number 84, is a rare and highly radioactive element. It was discovered in 1898 by Marie Curie and Pierre Curie. Chemically, polonium is similar to Bismuth. It is one of the radioactive daughter products in uranium ( 238 U) series and hence occurs in uranium ores, along with another alpha emitter of radium isotope, 226 Ra, to the extent of 0.2% of the 226 Ra. Because of its small abundance, the separation of polonium is very difficult. However, it can now be produced by irradiation of bismuth ( 209 Bi) by high energy neutrons. Major part of the legal 210 Po available is produced in Russia.
The half time of 210 Po is 138 days. It emits alpha particles during the decay, and the decay product is stable lead isotope - 206 Pb. Its parent, 210 Bi has a half-life of 5 days, and it emits beta particles. The energy of the alpha particle emitted by 210 Po is 5.3 million electron volts. Because of its shorter half-life, specific activity, that is, radioactivity per gram of the material is very high. In comparison, 1 mg of 210 Po emits as many alpha particles as 5 g of 226 Ra, with a half-life of 1600 years! One gram sample of 210 Po will spontaneously get heated up to above 500°C, generating about 140 watts of power. The uses of 210 Po are in space probes, antistatic devices and as neutron and alpha source.
While handling polonium, it easily gets airborne. If a polonium sample is heated to 55°C, 50% of the material gets vaporized. This is in-spite of the fact that the melting point and boiling point of polonium are high at 254°C and 962°C respectively.
Polonium is handled in specially designed air-tight boxes called glove boxes, with adequate negative pressure inside so that the contaminated air inside the box is not coming out into the working environment. High-performance gloves are used to prevent any possible diffusion of polonium inside the gloves and contaminate the hands of the working personnel. Use of torn/damaged gloves should never be used. The off-gas from the glove box is double-filtered through high-efficiency particulate air filters before its release into the environment. Appropriate monitoring of the workplace and individuals handling polonium, are carried out to ensure radiological safety.
Polonium is highly radiotoxic in the human body because its' high-energy alpha particle emissions. In the body, there is no biological role for polonium. By mass basis, 210 Po is 250,000 times more toxic than hydrogen cyanide. The lethal dose is as low as 1 μg for an average adult.
Polonium can be easily absorbed (transcutaneous diffusion) through intact skin. Other modes of intake into the body are inhalation of the airborne polonium or ingestion of the polonium contaminated food or water. The target organs for polonium in the body include spleen, liver, bone marrow and thymus.
In view of the nature of the handling hazard, any work with polonium is strictly regulated by national regulatory body.